What is the Difference Between Anoxic and Hypoxic Brain Injury

The key difference between anoxic and hypoxic brain injury is that, in anoxic brain injury, brain cells begin to die within a few minutes due to the complete cut off of oxygen to the brain, while in hypoxic brain injury, brain cells begin to die gradually due to a reduced or restricted flow of oxygen to the brain.

The brain needs a continuous supply of oxygen in order to function properly and survive. If the oxygen supply is interrupted, the functioning of the brain is disrupted. It can also cause irreversible damage to the brain. This is known as a brain injury due to oxygen deprivation. Oxygen deprivation occurs in two ways. Oxygen supply can be completely cut off (anoxic), or it can be a reduced or restricted supply of oxygen for a few minutes (hypoxic). In both conditions, the brain suffers due to insufficient levels of oxygen.

CONTENTS

1. Overview and Key Difference
2. What is Anoxic Brain Injury
3. What is Hypoxic Brain Injury
4. Similarities – Anoxic and Hypoxic Brain Injury
5. Anoxic vs Hypoxic Brain Injury in Tabular Form
6. Summary – Anoxic vs Hypoxic Brain Injury

What is Anoxic Brain Injury?

Anoxic brain injury is a type of brain injury due to the complete deprivation of oxygen to the brain. When the brain is left without oxygen completely for too long, the neural cells begin to die. This process is called apoptosis. When a large number of brain cells die simultaneously, it causes diminished brain function. If this condition continues for a long period of time, anoxic brain injury may become fatal. Anoxic brain injury can occur in situations like oxygen deprivation at birth among babies, a traumatic attack, a stroke, a transient ischemic attack (TIA), choking, anaphylactic shock due to allergic reactions, swallowing one’s own vomit, drug overdose, and a sudden blow to the windpipe. Immediately after an anoxic brain injury, some telltale symptoms may occur, such as confusion, loss of consciousness, feeling woozy or dizzy, vomiting, changes in behavior, and very intense headache.

Anoxic brain injury can be diagnosed through angiograms, imaging tests like CT scans or MRI, and electroencephalograms (EEG). Furthermore, the treatment options for anoxic brain injury include restoring good oxygen supply to the brain, medications to get heartbeat and blood pressure under control, a medically induced cooling method called therapeutic hypothermia to protect the brain, speech therapy, participating in a support group, family support and mental health counselling, occupational therapy, physical therapy, nutritional and exercise support and counselling.

What is Hypoxic Brain Injury?

Hypoxic brain injury is due to a restricted or reduced flow of oxygen to the brain. This restricted flow of oxygen causes gradual death and impairment of neural cells in the brain. The causes of hypoxic brain injury are choking, strangulation or suffocation, drowning, electrocution, head injury, heart attack, substance use disorder, carbon monoxide poisoning, seizure, severe blood loss, surgical complications, or anaesthesia problems. The signs and symptoms of hypoxic brain injury may include appearing disoriented and slurring words, breathing rapidly or shallowly, getting a bluish or grayish tint to skin or lips, having dilated pupils, convulsions, seizures, and not responding to the name when calling.

Hypoxic brain injury is diagnosed through angiography, CT scan or MRI, electroencephalogram (EEG), and evoked potentials test. Treatment options for hypoxic brain injury include supplying adequate oxygen to the brain, artificially cooling the body temperature, and giving medicine like physostigmine, physical therapy, occupational therapy, speech therapy, and psychological counselling.

What are the Similarities Between Anoxic and Hypoxic Brain Injury?

• Anoxic and hypoxic brain injury are two types of brain injury due to oxygen deprivation.
• Both conditions cause the death of neural cells in the brain.
• They can cause life-threatening complications.
• Both conditions can be diagnosed through brain imaging.
• They can be treated by supplying an adequate amount of oxygen to the brain.

What is the Difference Between Anoxic and Hypoxic Brain Injury?

Anoxic brain injury is a form of brain injury which happens due to a complete cut off of the oxygen to the brain, while hypoxic brain injury is a form of brain injury which happens due to a reduced flow of oxygen to the brain. Thus, this is the key difference between anoxic and hypoxic brain injury. Furthermore, anoxic brain injury results in the death of neural cells in the brain after approximately four minutes of oxygen deprivation. On the other hand, hypoxic brain injury results in gradual death and impairment of neural cells in the brain.

The below infographic presents the differences between anoxic and hypoxic brain injury in tabular form for side by side comparison.

Summary – Anoxic vs Hypoxic Brain Injury

Brain injuries can occur due to oxygen deprivation. It leads to functional interruptions of the brain. Anoxic and hypoxic brain injuries are two types of brain injuries occurring due to oxygen deprivation. Anoxic brain injury happens when the oxygen supply to the brain is completely cut off. In this condition, brain cells begin to die after four minutes of oxygen deprivation. On the other hand, hypoxic brain injury happens due to a reduced flow of oxygen to the brain. In this condition, brain cells start to die gradually. Both situations can be life-threatening. So, this is the summary of the difference between anoxic and hypoxic brain injury.

Reference:

1. “Anoxic and Hypoxic Brain Injury.” Anoxic and Hypoxic Brain Injury Treatment | Shepherd Center.
2. “Hypoxic Brain Injury.” Aapmr.org.

Image Courtesy:

1. “Anoxicbraininjury” By James Heilman, MD – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Computed tomography of human brain – large” By Department of Radiology, Uppsala University Hospital. Uploaded by Mikael Häggström. – Radiology, Uppsala University Hospital. Uploaded by Mikael Häggström. (CC0) via Commons Wikimedia